Existing methods to verify the proper positioning of an endotracheal tube (ETT) have been shown to have limited sensitivity and specificity. There are two strategies used to determine ETT placement: methods that detect the physiological results of moving air through the ETT and methods that attempt to detect the location of the ETT using imaging and/or that exploit the inherent characteristics the trachea or esophagus or of their relationship to the ETT within them.
Methods that detect the physiological results of moving air through the ETT include 1) observing for the movement of the chest or for distension of the abdomen 2) auscultating the axillae and stomach with a stethoscope and listening for breath sounds emanating from the lungs or for gurgling from the stomach 3) observing for the presence of condensation in the ETT 4) using capnography or capnometry devices that attach to the ETT and detect the presence of carbon dioxide with respiration 5) the use of pulse oximetry to detect the level of oxy-hemoglobin in a patient's blood 6) using microphones and whistles attached to the proximal or distal end of the ETT to detect differences in air flow during spontaneous respiration and/or 7) detecting differences in the precise exhaled oxygen concentrations.
Methods that attempt to detect the location of the ETT using imaging and/or that use the inherent characteristics of the trachea or esophagus or of their relationship to the ETT within them include 8) the use of devices that attach to the proximal end of the ETT and measure the refilling time of a compressed bulb or evacuated syringe 9) rapid inflation and deflation of the airway occlusion cuff (AOC) with palpation of the neck at the suprasternal notch 10) the use of chest x-rays 11) acoustic reflectometry which uses computer analysis of an acoustic impulse echo to reconstruct the anatomy distal to the ETT 12) transtracheal illumination with the use of a lighted stylet 13) detection of the presence of the ETT within the trachea using an ultrasound probe placed on the patient's neck 14) measuring the strength of a magnetic field created between a magnet attached to the distal end of an ETT and one placed over the patient's neck 15) measuring the impedance between two electrodes placed on the patient's chest 16) the use of radio frequency identification (RFID) tags to identify movement of the ETT after correct positioning and/or 17) using a camera built in to the ETT that allows for a continuous video feed of the view from the distal end of the ETT.
The problems associated with the above methods are multiple. Therefore, a need exists for an improved method and device to verify the proper positioning of the ETT.